The present application relates to vehicle braking systems, and is particularly directed to a brake assembly apparatus for a vehicle braking system, such as a heavy vehicle braking system that includes a drum brake assembly.
A typical drum brake assembly of a heavy vehicle, such as a truck, includes a brake shoe that engages a wheel drum to transmit braking torque through a brake spider to an axle. One end of the brake shoe is pivotable against an anchor pin that is attached to one side of the brake spider. A cam follower roller is disposed at the other end of the brake shoe. When a service brake application occurs, a camshaft located on an opposite side of the brake spider is actuated to rotate about its longitudinal central axis. As the camshaft rotates about its longitudinal central axis, a cam surface of an S-cam mounted on the camshaft acts against the cam follower roller to pivot the brake shoe about the anchor pin. As the brake shoe pivots about the anchor pin, brake lining of the brake shoe frictionally engages the wheel drum to transmit braking torque through the brake spider to the axle and thereby to decelerate and brake the vehicle.
During a service brake application, brake vibration may be created between the wheel drum and the brake shoe lining. The brake vibration between the wheel drum and the brake shoe lining could be transferred to other brake components, such as the camshaft, which may create an undesirable frequency vibration. This undesirable frequency vibration could then be transferred back (i.e., feedback vibration) through the brake shoe to the wheel drum to cause an objectionable level of noise. It would be desirable to damp such feedback vibration caused by the camshaft to reduce the objectionable level of noise to an unobjectionable level.